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[Qemu-arm] [PATCH for-4.1] target/arm: Stop using variable length array

From: Peter Maydell
Subject: [Qemu-arm] [PATCH for-4.1] target/arm: Stop using variable length array in dc_zva
Date: Thu, 28 Mar 2019 14:30:03 +0000

Currently the dc_zva helper function uses a variable length
array. In fact we know (as the comment above remarks) that
the length of this array is bounded because the architecture
limits the block size and QEMU limits the target page size.
Use a fixed array size and assert that we don't run off it.

Signed-off-by: Peter Maydell <address@hidden>
A small move in the direction of "avoid using variable length
arrays in QEMU"...

 target/arm/helper.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/target/arm/helper.c b/target/arm/helper.c
index a36f4b3d699..1b6225cb598 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -1,4 +1,5 @@
 #include "qemu/osdep.h"
+#include "qemu/units.h"
 #include "target/arm/idau.h"
 #include "trace.h"
 #include "cpu.h"
@@ -12412,11 +12413,13 @@ void HELPER(dc_zva)(CPUARMState *env, uint64_t 
          * same QEMU executable.
         int maxidx = DIV_ROUND_UP(blocklen, TARGET_PAGE_SIZE);
-        void *hostaddr[maxidx];
+        void *hostaddr[DIV_ROUND_UP(2 * KiB, 1 << TARGET_PAGE_BITS_MIN)];
         int try, i;
         unsigned mmu_idx = cpu_mmu_index(env, false);
         TCGMemOpIdx oi = make_memop_idx(MO_UB, mmu_idx);
+        assert(maxidx <= sizeof(hostaddr));
         for (try = 0; try < 2; try++) {
             for (i = 0; i < maxidx; i++) {

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